Construction machinery is used in renovating, reconstructing and extending buildings, for example. Wall saws are used for cutting and extending openings for doors, windows and light wells, etc., corrective work on facades, partition walls and garden walls, etc., and controlled demolition of concrete. Wall saws and similar construction machinery have a prime mover, such as a motor, and a rotary tool driven by the motor. In a wall saw, the tool is a circular saw blade equipped with cutting diamonds. Generally, heavy duty wall saws are driven hydraulically, see U.S. Pat. No. 6,955,167 B2, US 2006/0201492 A1, US 2007/0163492 A1, and U.S. Pat. No. 5,887,579, for example. However, hydraulic wall saws are comparatively heavy and not easy to set up, and comparatively low-weight electric wall saws, such as the one disclosed in US 2006/0189258 A1, for example, have been introduced on the market.
For certain tasks, wire saws are preferable over wall saws. As an example, they can make a cut much thinner than a blade-based saw is capable of. They can also cut through much thicker objects than a blade based saw is capable of, since the maximum depth of the cut is set by the radial distance between the periphery of the saw blade and its hub.
When operating a wire saw tension variations, e.g. whips or jerks in the wire, may increase wear of the wire, shorten its life length, and possibly affect other components of the wire saw negatively. Furthermore, sawing performance may be decreased. Such tensions may occur when the saw wire comes into contact with an area of other density or hardness in the object to be sawed than surrounding areas, e.g. stones or reinforcement bars in concrete.
In U.S. Pat. No. 5,472,262, guide pulleys are provided with suspensions to dampen vibrations and whip in the associated wire saw during the cutting operation. However, it would be advantageous if jerks and whips could be counteracted in a more efficient manner.
Furthermore, for some construction contractors it would be advantageous to have a single machine, which by dismounting some components from one version of the machine and installing other components from an accessory kit easily could be converted to another version, e.g. a wall saw into a wire saw and the other way round.
DE 298 05 157 U1, DE 298 05 457 U1, and EP 0 904 907 are further examples of wire saws.
Furthermore it would be advantageous with a wire saw that can saw close to corners, regardless if they are left or right corners.